This invention relates to certain transition metal compounds from Group 3 of the Periodic Table of Elements, and to a catalyst system comprising a Group 3 or Lanthanide transition metal compound and alumoxane, modified alumoxane, non-coordinating anion activator, Lewis acid, or the like to form an active cationic catalyst species for the production of polyolefins such as polyethylene, polypropylene and alpha-olefin copolymers of ethylene and propylene having a high molecular weight.
Neutral scandium compounds having two univalent ancillary ligands or a bidentate, divalent ancillary ligand are known from Shapiro et al., Organometallics, vol. 9, pp. 867-869 (1990); Piers et al., J. Am. Chem Soc., vol. 112, pp. 9406-9407 (1990); Shapiro et al., J. Am. Chem Soc., vol. 116, pp. 4623-4640 (1994); Hajela et al., Organometallics, vol. 13, pp. 1147-1154 (1994); and U.S. Pat. No. 5,563,219 to Yasuda et al. Similar yttrium, lanthanum and cerium complexes are disclosed in Booij et al., Journal of Organometallic Chemistry, vol. 364, pp. 79-86 (1989) and Coughlin et al., J. Am. Chem. Soc., vol. 114, pp. 7606-7607 (1992). Similar polymerizations with a metal scandium complex having a bidentate, divalent ancillary ligand using a non-ionizing cocatalyst is known from U.S. Pat. No. 5,464,906 to Patton et al.
Group 3-10 metallocyclic catalyst complexes are described in U.S. Pat. Nos. 5,312,881 and 5,455,317, both to Marks et al.; U.S. Pat. No. 5,064,802 to Stevens et al.; and EP 0 765 888 A2.
Polymerization of olefins with cationic Group 4 metal complexes is illustrated in WO 96/13529 and WO 97/42228. Boratabenzene complexes of Group 3-5 metals are disclosed in WO 97/23493.
Amidinato complexes of Group 3-6 metals are disclosed in U.S. Pat. No. 5,707,913 to Schlund et al. Group 4 bisamido catalysts are disclosed in U.S. Pat. No. 5,318,935 to Canich, et al., and related bidentate bisarylamido catalysts are disclosed by D. H. McConville, et al, Macromolecules 1996, 29, 5241-5243.
The present invention is directed to a catalyst system for coordination polymerization comprising a cationic Group 3 or Lanthanide metal stabilized by a monoanionic bidentate ancillary ligand and two monoanionic ligands. The ancillary ligand, together with the metal, forms a metallocycle comprising a ring of at least five primary atoms, counting any xcex75-bonded cyclopentadienyl in the metallocycle as two primary metallocycle atoms. The metal is preferably scandium, yttrium or lanthanum.
In one embodiment, the monoanionic bidentate ancillary ligand, A, has the formula (C5H4-xRx)TE wherein x is a number from 0 to 4 denoting the degree of substitution; each R is, independently, a radical selected from C1-C20 hydrocarbyl radicals, C1-C20 substituted hydrocarbyl radicals wherein one or more hydrogen atoms are replaced by a halogen atom, amido, phosphido, alkoxy or aryloxy or any other radical containing a Lewis acidic or basic functionality, C1-C20 hydrocarbyl-substituted metalloid radicals wherein the metalloid is selected from Group 14 of the Periodic Table of the Elements, and halogen radicals, or C5H4-xRx is a cyclopentadienyl ring in which two adjacent R-groups are joined to form a C4-C20 ring to give a saturated or unsaturated polycyclic cyclopentadienyl ligand which may additionally be substituted with R groups, and may contain a heteroatom within the ring; T is a covalent bridging group containing a Group 14 or 15 element; and E is a xcfx80 donating hydrocarbyl, xcfx80 donating heterohydrocarbyl, or other xcfx80-donating ligand covalently bound to T such as, for example, allyl, phenyl, benzyl, pyridyl or the like, or E is JRxe2x80x2z wherein J is an element from Group 15 or 16, z is 2 when J is a Group 15 element and 1 when J is a Group 16 element, each Rxe2x80x2 is independently a radical selected from C1-C20 hydrocarbyl radicals, substituted C1-C20 hydrocarbyl radicals wherein one or more hydrogen atoms is replaced by a halogen atom, and C1-C20 hydrocarbyl-substituted metalloid radicals wherein the metalloid is selected from Group 14 of the Periodic Table of the Elements.
Heterocyclic pi donating ligands wherein one to three ring carbons of the C5H4-xRx ligand is replaced by a Group 15 or 16 heteroatom; substituted or unsubstituted boratabenzene ligands; substituted or unsubstituted allyl ligands; substituted or unsubstituted pentadienyl ligands; or other delocalized pi-bonded ligands may also be used in place of the C5H4-xRxligand.
In another embodiment, as represented by structure (I), the monoanionic bidentate ancillary ligand, A, has the formula xe2x80x94NRxe2x80x2=Txe2x80x2xe2x80x94NRxe2x80x2-wherein N is nitrogen and Txe2x80x2 is a covalent bridging group selected from xe2x95x90C(R)-[C(R)xe2x95x90C(R)]xcex7- and 
wherein each Rxe2x80x2 is independently as defined above, each R is independently as defined above, except that R independently may also be hydrogen except for R groups attached to the carbon atoms directly bonded to the nitrogen atoms.
In a further embodiment, a typical polymerization process according to the present invention, such as the polymerization or copolymerization of olefins, comprises the steps of activating the transition metal component to a cationic form and contacting ethylene or C3-C20 alpha-olefins alone or with other unsaturated monomers including C3-C20 alpha-olefins, C5-C20 diolefins, and/or acetylenically unsaturated monomers, either alone or in combination with other olefins and/or other unsaturated monomers, with a catalyst comprising, in a suitable polymerization diluent, the activated cationic transition metal component of the invention. The catalyst is activated with an alumoxane, modified alumoxane, non-coordinating anion activator, Lewis acid or the like, or combinations, in an amount to provide a molar ratio of aluminum, non-coordinating anion, or Lewis acid to transition metal of from about 1:10 to about 20,000:1 or more; and reacts with the monomer(s) at a temperature from about xe2x88x92100xc2x0 C. to about 300xc2x0 C. for a time from about one second to about 10 hours to produce a polyolefin having a weight average molecular weight of from about 1000 or less to about 5,000,000 or more and a molecular weight distribution of from about 1.5 to about 15.0 or greater.
The Group 3 transition metal component of the catalyst system of the invention can be defined broadly by the formula: 
wherein M is a Group 3 or Lanthanide metal;
A is a monoanionic, bidentate ancillary ligand which forms a metallocycle with M comprising at least 5 primary atoms, provided that any cyclopentadienyl group or other delocalized pi-bonded ligand in the metallocycle is counted as two primary metallocycle atoms; each Q is independently a monoanionic ligand such as a radical selected from halide, hydride, substituted or unsubstituted C1-C20 hydrocarbyl, hydrocarbylsilyl, alkoxide, aryloxide, amide or phosphide or both Q together may be an alkylidene or a cyclometallated hydrocarbyl or any other divalent anionic chelating ligand, or a diene, with the proviso that where any Q is a hydrocarbyl radical, such Q is not a substituted or unsubstituted cyclopentadienyl radical;
L is a neutral Lewis base such as, for example, diethyl ether, tetrahydrofuran, dimethylaniline, trimethylphosphine, lithium chloride or the like, and can also be optionally covalently bound to one or both Q, provided Q is not hydride or halide. L can also be a second transition metal of the same type, i.e. the transition metal component can be dimeric; and
w is a number from 0 to 3.
In cationic form as activated for olefin polymerization, the transition metal complex has the formula: 
wherein M, A, Q, L and w are as defined above and Axe2x80x2 is a weakly or noncoordinating anion which counterbalances the cationic complex.
In a preferred embodiment, the transition metal component of the catalyst system has the formula: 
wherein C5H4-xRx is typically a cyclopentadienyl ring covalently xcfx80-bound to M and substituted with from zero to four substituent groups R, x is a number from 0 to 4 denoting the degree of substitution, and each R is, independently, a radical selected from C1-C20 hydrocarbyl radicals, C1-C20 substituted hydrocarbyl radicals wherein one or more hydrogen atoms are replaced by a halogen atom, amido, phosphido, alkoxy or aryloxy or any other radical containing a Lewis acidic or basic functionality, C1-C20 hydrocarbyl-substituted metalloid radicals wherein the metalloid is selected from Group 14 of the Periodic Table of the Elements, and halogen radicals, or C5H4-xRx is a cyclopentadienyl ring in which two adjacent R-groups are joined to form a C4-C20 ring to give a saturated or unsaturated polycyclic cyclopentadienyl ligand which may additionally be substituted with R groups, and may contain a heteroatom within the ring; C5H4-xRx may alternatively be replaced with a heteroatom-containing 5-membered monovalent anionic ring group covalently xcfx80-bound to M, said heteroatoms being selected from the non-carbon Group 13-15 atoms, preferably boron, silicon, germanium, nitrogen or phosphorus. Most typically one heteroatom will replace one of the carbon atoms in the 5-member ring. Additionally, two or more adjacent R groups may be joined to form a 4 to 20 atom ring forming a saturated or unsaturated polycyclic cyclopentadienyl ligand which may additionally contain a non-carbon group 14-16 heteroatom within the ring. Such ligands are described in WO 98/22486 which is referred to for information and incorporated by reference for purposes of U.S. patent practice.
T is a covalent bridging group containing a Group 14 or 15 element such as, but not limited to, a dialkyl, alkylaryl or diaryl silicon or germanium radical, alkyl or aryl phosphine or amine radical, or a hydrocarbyl radical such as methylene, ethylene, isopropylene or the like.
J is a Group 15 or 16 element; z is 2 when J is a Group 15 element and 1 when J is a Group 16 element; each R is independently a radical selected from C1-C20 hydrocarbyl radicals and substituted C1-C20 hydrocarbyl radicals wherein one or more hydrogen atoms is replaced by a halogen atom, amido, phosphido, alkoxy, aryloxy, metalloid or any other radical containing a Lewis acidic or basic functionality, and C1-C20 hydrocarbyl-substituted metalloid radicals wherein the metalloid is selected from Group 14 of the Periodic Table of the Elements.
Q, L and w are defined above.
Exemplary hydrocarbyl radicals for Q in all of the above formulae are methyl, ethyl, propyl, butyl, amyl, isoamyl, hexyl, isobutyl, heptyl, octyl, nonyl, decyl, cetyl, 2-ethylhexyl, phenyl, benzyl and the like, with benzyl being preferred. Exemplary halogen atoms for Q include chlorine, bromine, fluorine and iodine, with chlorine being preferred. Exemplary alkoxides and aryloxides for Q are methoxide, phenoxide and substituted phenoxides such as 4-methyl-phenoxide. Exemplary amides for Q are dimethylamide, diethylamide, methylethylamide, di-t-butylamide, diisopropylamide and the like. Exemplary arylamides are diphenylamide and any other substituted phenylamides. Exemplary phosphides for Q are diphenylphosphide, dicyclohexylphosphide, diethylphosphide, dimethylphosphide and the like. Exemplary alkylidene radicals for both Q together are methylidene, ethylidene and propylidene. Exemplary cyclometallated hydrocarbyl radicals for both Q together are propylene, and isomers of butylene, pentylene, hexylene and octylene. Exemplary dienes for both Q together are 1,3-butadiene, 1,3-pentadiene, 1,4-pentadiene, 1,3-hexadiene, 1,4-hexadiene, 1,5-hexadiene, 2,4-dimethyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 2-methyl-1,3-hexadiene and 2,4-hexadiene.
Suitable hydrocarbyl radicals, for R or Rxe2x80x2 in all the above formulae, will contain from 1 to about 20 carbon atoms and include straight and branched alkyl radicals, cyclic hydrocarbon radicals, alkyl-substituted cyclic hydrocarbon radicals, aromatic radicals, alkyl-substituted aromatic radicals. Suitable substituted hydrocarbyl radicals are hydrocarbyl radicals as defined above which are independently substituted with one or more halogen, amido, phosphido, alkoxy, metalloid or other Lewis acidic or basic functionality, such as, trifluoromethyl, dimethylaminomethyl, diphenylphosphinomethyl, methoxymethyl, phenoxyethyl trimethylsilylmethyl and the like. Suitable organometallic radicals for R or Rxe2x80x2, in all the above formulae include trimethylsilyl, triethylsilyl, ethyldimethylsilyl, methyldiethylsilyl, triphenylgermyl and the like.
In cationic form activated for olefin polymerization, the monocyclopentadienyl transition metal complex has the formula: 
wherein M, C5H4-xRxR, x, T, J, z, Rxe2x80x2, L, w and Axe2x80x2 are as defined above.
In an alternative embodiment, the transition metal component of the catalyst system has one of the formulae: 
wherein n is 1, 2, 3 or 4 and M, N, Q, L, w, Rxe2x80x2 and R are as defined above, except that R independently may also be hydrogen except for the R groups attached to the carbon atoms directly bonded to the nitrogen atoms.
In cationic forms activated for olefin polymerization the transition metal complexes of formulae (VI) and (VII) have the representative formulae: 
wherein M, N, R, Rxe2x80x2, Q, L, w, n and Axe2x80x2 are as defined above.
Table 1 below depicts representative constituent moieties for the Group 3 or Lanthanide transition metal components of the present catalyst system, but the list is for illustrative purposes only and should not be construed to be limiting in any way. A number of final compounds may be formed by permuting possible combinations of the constituent moieties with each other. Some changes in nomenclature may be required. For example, if 1,2-dimethylcyclopentadienyl is bridged via the xe2x80x9c5xe2x80x9d position, it can become 2,3-dimethylcyclopentadienyl. When a specific isomer is not specified, all possible isomers are included. For example, when Q=propoxy, n-propoxy, and i-propoxy are included. Specific representative examples include cyclopentadienyl-dimethylsilylene-pyridyl-scandium-dihydride; methylcyclopentadienyl-phenylene-dimethylamino-yttrium-dichloride; tetramethylcyclopentadienyl-methylphenylsilylene-diphenylamino-lanthanum-diethyl; and the like.
Metal complexes according to the invention can be prepared by various conventional synthetic routes.
The metal compounds according to the invention are suitable for coordination polymerization when activated by methods known in the metallocene art. Suitable activators typically include alumoxane compounds, modified alumoxane compounds, and ionizing anion precursor compounds that abstract one reactive, sigma bound metal ligand thereby ionizing the metal center into a cationic complex and providing a counter-balancing weakly or noncoordinating anion, which can optionally be bound to the cationic complex so as to form a Zwitterionic catalyst.
Alkylalumoxanes and modified alkylalumoxanes are suitable as catalyst-activators, particularly for the invention metal compounds comprising halide ligands. The alumoxane component useful as a catalyst activator typically is an oligomeric aluminum compound represented by the general formula (R2xe2x80x94Alxe2x80x94O)m, which is a cyclic compound, or R3(R4xe2x80x94Alxe2x80x94O)mAlR2, which is a linear compound, although other structural variations may exist. In the general alumoxane formula each R2-R5 is independently a C1 to C20 hydrocarbyl radical, for example, methyl, ethyl, and isomers of propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl or icosyl, and m is an integer from 1 to about 50. Most preferably, R2-R5 is methyl and m is at least 4. If an alkyl aluminum halide is used in the alumoxane preparation, the R2-R5 can also be halide. Alumoxanes can be prepared by various procedures known in the art. For example, an aluminum alkyl may be treated with water dissolved in an inert organic solvent, or it may be contacted with a hydrated salt, such as hydrated copper sulfate suspended in an inert organic solvent, to yield an alumoxane. Generally, however prepared, the reaction of an aluminum alkyl with a limited amount of water yields a mixture of the linear and cyclic species of the alumoxane. Methylalumoxane and modified methylalumoxanes are preferred. Mixtures of different alumoxanes and modified alumoxanes may also be used. For further descriptions, see U.S. Pat. Nos. 4,665,208, 4,952,540, 5,041,584, 5,091,352, 5,206,199, 5,204,419, 4,874,734, 4,924,018, 4,908,463, 4,968,827, 5,329,032, 5,248,801, 5,235,081, 5,157,137, 5,103,031 and EP 0 561 476 A1, EP 0 279 586 B1, EP 0 516 476 A, EP 0 594 218 A1 and WO 94/10180, each being incorporated by reference for purposes of U.S. patent practice.
When the activator is an alumoxane, the preferred transition metal compound to activator molar ratio is from about 1:5000 to 1:1, more preferably from about 1:1000 to 1:10, even more preferably from about 1:500 to 1:10 and most preferably from about 1:100 to 1:10.
The term xe2x80x9cnoncoordinating anionxe2x80x9d is recognized to mean an anion, as-represented by the symbol Axe2x80x2 above, which either does not coordinate to the metal cation or which is only weakly coordinated to it thereby remaining sufficiently labile to be displaced by a neutral Lewis base, such as an olefinically or acetylenically unsaturated monomer.
Descriptions of ionic catalysts, those comprising a transition metal cationic complex and a noncoordinating anion, suitable for coordination polymerization appear in the early work in U.S. Pat. Nos. 5,064,802, 5,132,380, 5,198,401, 5,278,119, 5,321,106, 5,347,024, 5,408,017, 5,599,671, and WO 92/00333 and WO 93/14132. These teach a preferred method of preparation wherein metallocenes are protonated by noncoordinating anion precursors such that an alkyl/hydride group is abstracted making the transition metal compound both cationic and charge-balanced by the noncoordinating anion. Since similar ligands may be present in the metal compounds of the invention, similar methods of activation to prepare active polymerization catalysts may be followed. A preferred hydrocarbyl radical Q serving as an abstractable ligand is benzyl.
Preferred noncoordinating anion precursors of this type include those of formula [R*3GH][ZX*4-aR*a] where R* is independently a C1-30 hydrocarbyl, fluorohydrocarbyl, hydrocarbylsilyl or other substituted hydrocarbyl group, G is a Group 15 element, preferably nitrogen, H is a proton capable of reacting with the Group 3 or Lanthanide metal complex, Z is a group 13 element, preferably boron or aluminum, X* is independently a substituted or unsubstituted fluorocarbyl or fluorohydrocarbyl ligand, preferably a substituted or unsubstituted aromatic fluorocarbyl or fluorohydrocarbyl ligand, and a is 0, 1 or 2. Most preferred X* radicals include perfluorophenyl, perfluoronapthyl, perfluorobiphenyl, and 3,5-bis(trifluoromethyl)phenyl. The preferred cationic portion of the noncoordinating anion precursors include [Me2PhNH], [n-Bu3NH], [(C18H37)2PhNH], [(C16H33)3NH], [(C18H37)3NH] and the like. The preferred anionic portion of the noncoordinating anion precursors include [B(C6F5)4], [B(C10F7)4], [B(C12F9)4], [MeB(C6F5)3], [B(3,5-(CF3)2C6H3) 4], [B(C6F5)3(C10F7)] and the like where C6F5 is perfluorophenyl, C10F7 is perfluoronapthyl and C12F9 is perfluorobiphenyl.
The use of ionizing ionic compounds not containing an active proton but capable of producing both an active metal cationic complex and a noncoordinating anion is also possible. See, EP-A-0 426 637, EP-A-0 573 403 and U.S. Pat. No. 5,387,568 for instructive ionic compounds. Reactive cations of the ionizing ionic compounds, other than the Bronsted acids, include ferrocenium, silver, tropylium, carbenium cations including triphenylcarbenium and silylium cations including triethylsilylium, or alkali metal or alkaline earth metal cations such as sodium, magnesium or lithium cations. A further class of noncoordinating anion precursors suitable in accordance with this invention are hydrated salts comprising the alkali metal or alkaline earth metal cations and a non-coordinating anion as described above. The hydrated salts can be prepared by reaction of the metal cation-noncoordinating anion salt with water, for example, by hydrolysis of the commercially available or readily synthesized [Li]+[B(pfp)4]xe2x88x92 which yields [Li(H2O)x]+[B(pfp)4]xe2x88x92, where (pfp) is pentafluorophenyl or perfluorophenyl.
Any metal or metalloid capable of forming a compatible, weakly or negligibly coordinating complex may be used or contained in the noncoordinating anion. Suitable metals include, but are not limited to aluminum, gold, platinum and the like. Suitable metalloids include, but are not limited to, boron, phosphorus, silicon and the like. The description of noncoordinating anions and precursors thereto of the documents of the foregoing paragraphs are incorporated by reference for purposes of U.S. patent practice.
An additional method of making the active polymerization catalysts of this invention uses ionizing anion precursors which are initially neutral Lewis acids but form a metal cationic complex and the noncoordinating anion, or a Zwitterionic complex upon reaction with the invention compounds. For example, tris(pentafluorophenyl) boron or aluminum act to abstract a hydrocarbyl or hydride ligand to yield an invention metal cationic complex and stabilizing noncoordinating-anion, see EP-A-0 427 697 and EP-A-0 520 732 for illustration utilizing analogous Group 4 metallocene compounds. See also the methods and compounds of EP-A-0 495 375. For formation of Zwitterionic complexes using analogous Group 4 compounds see U.S. Pat. Nos. 5,624,878; 5,486,632; and 5,527,929. The description of noncoordinating anions and precursors thereto of these documents are similarly incorporated by reference for purposes of U.S. Patent practice. Lewis acid activators include those of formula ZX*3-bR*b where Z, X* and R* are as defined above and b is 0 or 1. Preferred Lewis acid activators include B(C6F5)3, Al(C6F5)3, B(C10F7)3, Al(C10F7)3, B(C12F9)3, Al(C12F9)3 and the like.
When the cation portion of an ionic noncoordinating anion precursor is a Bronsted acid such as protons or protonated Lewis bases (excluding water), or a reducible Lewis acid such as ferrocenium or silver cations, or alkaline metal or alkaline earth metal cations such as those of sodium, magnesium or lithium cations, or a neutral Lewis base such as B(C6F5)3 or Al(C6F5)3, the transition metal to activator molar ratio may be any ratio, but preferably from about 10:1 to 1:10, more preferably from about 5:1 to 1:5, even more preferably from about 2:1 to 1:2 and most preferably from about 1.2:1 to 1:1.2 with the ratio of about 1:1 being the most preferred. Combinations of the activator compounds described may also be used for activation. For example, tris(perfluorophenyl) boron can be used in conjunction with methylalumoxane.
The catalyst complexes of the invention are useful in polymerization of unsaturated monomers conventionally known to be polymerizable under coordination polymerization conditions using metallocenes. Such conditions are well known and include solution polymerization, slurry polymerization, gas-phase polymerization, and high pressure polymerization. The catalyst of the invention may be supported and as such will be particularly useful in the known operating modes employing fixed-bed, moving-bed, fluid-bed, slurry or solution processes conducted in single, series or parallel reactors.
When using the catalysts of the invention, particularly when immobilized on a support, the total catalyst system will generally additionally comprise one or more scavenging compounds. The term xe2x80x9cscavenging compoundsxe2x80x9d as used in this application and its claims is meant to include those compounds effective for removing polar impurities from the reaction environment. Impurities can be inadvertently introduced with any of the polymerization reaction components, particularly with solvent, monomer and catalyst feed, and adversely affect catalyst activity and stability. It can result in decreasing or even elimination of catalytic activity, particularly when ionizing anion pre-cursors activate the catalyst system. The polar impurities, or catalyst poisons include water, oxygen, metal impurities, etc. Preferably steps are taken before provision of such into the reaction vessel, for example by chemical treatment or careful separation techniques after or during the synthesis or preparation of the various components, but some minor amounts of scavenging compound will still normally be used in the polymerization process itself.
Typically the scavenging compound will be an organometallic compound such as the Group 13 organometallic compounds of U.S. Pat. Nos. 5,153,157, 5,241,025 and WO-A-91/09882, WO-A-94/03506, WO-A-93/14132, and that of WO 95/07941. Exemplary compounds include triethyl aluminum, triethyl borane, triisobutyl aluminum, methylalumoxane, isobutyl aluminumoxane, and tri-n-octyl aluminum. Those scavenging compounds having bulky or C6-C20 linear hydrocarbyl substituents covalently bound to the metal or metalloid center are preferred to minimize adverse interaction with the active catalyst. Examples include triethylaluminum, but more preferably, bulky compounds such as triisobutylaluminum, triisoprenylaluminum, and long-chain linear alkyl-substituted aluminum compounds, such as tri-n-hexylaluminum, tri-n-octylaluminum, or tri-n-dodecylaluminum. When alumoxane is used as activator, any excess over the amount needed to activate the catalysts present will act as scavenger compounds and additional scavenging compounds may not be necessary. Alumoxanes also may be used in scavenging amounts with other means of activation, e.g., methylalumoxane, [Me2HNPh]+[B(pfp)4]xe2x88x92 or B(pfp)3. The amount of scavenging agent to be used with the catalyst compounds of the invention is minimized during polymerization reactions to that amount effective to enhance activity and avoided altogether if the feeds can be sufficiently free of adventitious impurities.
The catalyst according to the invention may be supported for use in gas phase, bulk, slurry polymerization processes, or otherwise as needed. Numerous methods of support are known in the art for copolymerization processes for olefins, particularly for catalysts activated by alumoxanes, any are suitable for the invention process in its broadest scope. See, for example, U.S. Pat. Nos. 5,057,475 and 5,227,440. An example of supported ionic catalysts appears in WO 94/03056. A particularly effective method is that described U.S. Pat. No. 5,643,847, and WO 96/04319. A bulk, or slurry, process utilizing supported, invention metal compounds activated with alumoxane co-catalysts can be utilized as described for ethylene-propylene rubber in U.S. Pat. Nos. 5,001,205 and 5,229,478, and these processes will additionally be suitable with the catalyst systems of this application. Both inorganic oxide and polymeric supports may be utilized in accordance with the knowledge in the field. See U.S. Pat. Nos. 5,422,325, 5,427,991, 5,498,582 and 5,466,649, and international publications WO 93/11172 and WO 94/07928. Each of the foregoing documents is incorporated by reference for purposes of U.S. patent practice.
In preferred embodiments of the process for this invention, the catalyst system is employed in liquid phase (solution, slurry, suspension, bulk phase or combinations thereof), in high pressure liquid or supercritical fluid phase, or in gas phase. Each of these processes may be employed in singular, parallel or series reactors. The liquid processes comprise contacting olefin monomers with the above described catalyst system in a suitable diluent or solvent and allowing said monomers to react for a sufficient time to produce the copolymers in accordance with the invention. Hydrocarbyl solvents are suitable, both aliphatic and aromatic, hexane and toluene are preferred. Bulk and slurry processes are typically done by contacting the catalysts with a slurry of liquid monomer, the catalyst system being supported. Gas phase processes typically use a supported catalyst and are conducted in any manner known to be suitable for ethylene homopolymers or copolymers prepared by coordination polymerization. Illustrative examples may be found in U.S. Pat. Nos. 4,543,399, 4,588,790, 5,028,670, 5,382,638, 5,352,749, 5,436,304, 5,453,471, and 5,463,999, and WO 95/07942. Each is incorporated by reference for purposes of U.S. patent practice.
Generally speaking the polymerization reaction temperature can vary from about xe2x88x9250xc2x0 C. to about 250xc2x0 C. Preferably the reaction temperature conditions will be from xe2x88x9220xc2x0 C. to 220xc2x0, more preferably below 200xc2x0 C. The pressure can vary from about 1 mm Hg to 2500 bar, preferably from 0.1 bar to 1600 bar, most preferably from 1.0 to 500 bar.
Linear polyethylene, including high and ultra-high molecular weight polyethylenes, including both homo- and copolymers with other alpha-olefin monomers, alpha-olefinic and/or non-conjugated diolefins, for example, C3-C20 olefins, C4-C20 diolefins, C4-C20 cyclic olefins or C8-C20 styrenic olefins, are produced by adding ethylene, and optionally one or more of the other monomers, to a reaction vessel at a typical temperature of 20-250xc2x0 C. with the invention catalyst that has been slurried with or dissolved in a solvent, such as hexane or toluene. Heat of polymerization is typically removed by cooling. Gas phase polymerization can be conducted, for example, in a continuous fluid bed gas-phase reactor operated at about 200-3000 kPa and 60-160xc2x0 C., using hydrogen as a reaction modifier (100-200 ppm), C4-C8 comonomer feedstream (0.5-12 mol %), and C2 feedstream (25-35 mol %). See, U.S. Pat. Nos. 4,543,399, 4,588,790, 5,028,670 and 5,405,922 and 5,462,999, which are incorporated by reference for purposes of U.S. patent practice.
Ethylene-xcex1-olefin (including ethylene-cyclic olefin and ethylene-xcex1-olefin-diolefin) elastomers of high molecular weight and low crystallinity can be prepared utilizing the catalysts of the invention under traditional solution polymerization processes or by introducing ethylene gas into a slurry utilizing the xcex1-olefin or cyclic olefin or mixtures thereof with other monomers, polymerizable and not, as a polymerization diluent in which the invention catalyst is suspended. Typical ethylene pressures will be between 10 and 1000 psig (69-6895 kPa) and the polymerization diluent temperature will typically be between xe2x88x9210-160xc2x0 C. The process can be carried out in a stirred tank reactor, or more than one reactor operated in series or parallel. See the general disclosure of U.S. Pat. No. 5,001,205 which is incorporated by reference for its description of polymerization processes, ionic activators and useful scavenging compounds.
Pre-polymerization of the supported catalyst of the invention may also be used for further control of polymer particle morphology in typical slurry or gas phase reaction processes in accordance with conventional teachings. For example, such can be accomplished by pre-polymerizing ethylene or a C3-C6 xcex1-olefin for a limited time, for example, ethylene is contacted with the supported catalyst at a temperature of xe2x88x9215xc2x0 to 30xc2x0 C. and ethylene pressure of up to about 250 psig (1724 kPa) for 75 min to obtain a polymeric coating on the support of polyethylene of 30,000-150,000 molecular weight. The pre-polymerized catalyst is then available for use in the polymerization processes referred to above. The use of polymeric resins as a support coating may additionally be utilized, typically by suspending a solid support in dissolved resin of such material as polystyrene with subsequent separation and drying.
Other olefinically unsaturated monomers besides those specifically described above may be polymerized using the catalysts according to the invention, for example, styrene, alkyl-substituted styrene, ethylidene norbornene, norbornadiene, dicyclopentadiene, vinylcyclohexane, vinylcyclohexene and other olefinically-unsaturated monomers, including other cyclic olefins, such as cyclopentene, -norbornene, and alkyl-substituted norbornenes. Additionally, xcex1-olefinic macromonomers of up to 1000 mer units, or more, may also be incorporated by copolymerization.
The catalyst compositions of the invention can be used as described above individually for coordination polymerization or can be mixed to prepare polymer blends with other known olefin polymerization catalyst compounds. By selection of monomers, blends of coordination catalyst compounds, polymer blends can be prepared under polymerization conditions analogous to those using individual catalyst compositions. Polymers having increased MWD for improved processing and other traditional benefits available from polymers made with mixed catalyst systems can thus be achieved.